After receiving initial approval in August 2016, the Foundation finally got the go-ahead for the “Delivering the Nutrient Management Plan” (DNMP) partnership project in January 2018.
Supported by the European Regional Development Fund, Environment Agency and Welsh Water, the project is rather less to do with nutrients than originally planned*. After 23 revisions to the project bid, DNMP now has three main areas of action:
- The Foundation would improve upstream and downstream fish access for salmon, trout and eels at 14 Lugg and Arrow weirs.
- Herefordshire Wildlife Trust would improve the structure and biodiversity of Bodenham lake by re-profiling the bank in three areas and establishing reedbeds.
- Welsh Water would stop clean water flowing into Rotherwas Sewage works from the Yazor aquifer to improve their ability to strip phosphate at the works, decreasing the levels of it in the Lower Wye by 3-7%.
Project objectives for the Foundation
For the Foundation, the major element of this project was a “Larinier” fish pass at Ballsgate weir on the middle reaches of the Lugg, the first pass of this style that the Foundation has built.
Although some fish species could use the existing baulk pass, they could only do so in certain water heights. This might not have been such a problem if Ballsgate was the only weir in the Lugg system. However, there are so many that the river is often likened to Grand National for migrating fish species. Also included in the project are smaller easements on the Lugg and one on the Arrow too.
While the fish passes will help migrating salmon, trout and grayling (Lugg passes), we will also be helping upstream migration of the endangered European eel. The project will enable us to install 100 metres of eel brushes on 8 Lugg and Arrow weirs.
Ballsgate Fish Pass
After a crayfish rescue at the construction site, physical work on the fish pass began in July 2019. The first job was to install a coffer dam above the weir and an inflatable bladder below. This is to ensure a dry area in which we can build the new concrete structure.
Work then began on the first phase with extra foundations needing to be built for the sluice that the pass was to be built off. We had originally planned to finish the pass for the 2019 salmon and trout migration and by early September we had completed this first phase. Then it started to rain, bringing fish pass work across the region to a halt.
After a winter of record floods, we resumed work at Ballsgate in the summer of 2020, completing phases two and three by August in time for the 2020 autumn migration.
The project is not just about upstream migration of fish species.
Understanding of the importance of weirs in downstream migration has been g
rowing in recent years. Young salmon (smolts) on their way to sea and brown trout are reluctant to enter water less than 12cm deep. In low flows shallow sill weirs can be a complete barrier to downstream migration.
Fish that collect above weirs in such conditions suffer heavy losses, where they are an easy target for a host of predators. During dry springtimes, the time of year when the majority of trout and young salmon migrate, it has been shown to result in as much as 100% predation in catchments with lots of weirs.
Within the DNMP project, the Foundation will cut and secure suitable notches into twelve Lugg and Arrow weirs that have been identified as barriers to downstream migration. In 2018, we increased the depth of the flow over the crest at four Arrow weirs. In addition, we have constructed a “smolt notch” on another Arrow weir where lowering the crest was not possible. This has eased downstream migration for juvenile salmon and trout of all ages plus other species.
We have also constructed new eel passes on two Arrow weirs and modified another.
The Foundation has been allocated £273,196 of the £1,225,000 combined budget for all the project’s partners. With this we will deliver the actions above by 2020.
We are very grateful to our project funders, the European Regional Development Fund and our partners Dwr Cymru Welsh Water, Herefordshire Wildlife Trust and Environment Agency.
* The main part of our original project was for farm advisory work but this was moved into another project leaving just the fish access work.